Effect of crystal composition on ``quasidirect'' recombination and LED performance in the indirect region of GaAs1−xPx:N

Abstract

The Koster-Slater one-band one-site model has been employed to investigate the modulus of the wave function of an electron bound to a N isoelectronic trap in GaAs1−xPx:N as a function of crystal composition x. The no-phonon recombination transition involving the trapped electron is enhanced as the crystal composition is changed to bring the Γ conduction band minimum, EΓ, near the N-trap level, EN. Absorption data taken on x = 1.0 and x = 0.53 GaAs1−xPx:N are consistent with the calculated increase in the probability density in the Γ region as EΓ decreases relative to EX. The change in the internal quantum efficiency as a function of crystal composition has been calculated assuming that the nonradiative component of recombination is independent of x. By weighting the internal recombination-radiation quantum efficiency by the photopic response of the eye, we have determined that the optimum range of crystal compositions in which to fabricate GaAs1−xPx:N LED's is 0.6 ≤ x ≤ 0.8. This result is in good agreement with current GaAs1−xPx :N LED fabrication processes.